The purpose of this research is to continue our study of a group of children with abnormalities of the sex chromosomes who were identified in a cytogenetic survey of 40,000 consecutive births from 1964-1974. Our long-term objective is to define the ultimate prognosis for each of these conditions--47,XXX; 47,XXY; 47,XYY; 45,X and mosaicisms of these. Data from biased samples of children and adults with these karyotypes indicate that they are at an increased risk for intellectual, emotional, social or physical problems in later life. The data from this "Family Development Study" are being analyzed by comparisons between subgroups and by using chromosomally normal siblings as controls. We have identified delayed language development as an important problem in many of the propositi, and are conducting an in-depth study in this area. The chief investigator and his associates have been receiving inquiries from all over the world as to the prognosis of fetuses identified in utero as having these karyotypes, thus stressing one significant result of these continuing studies.